At first read I was thinking classic life changes. I changed a lot in my 20s. But him ignoring the situation all together makes my head spin....

Is his personality and identity the same?

Does his parents notice anything different about him?

It seems like hardcore avoidance. I bet he's been going to the bar a lot and is struggling with identity issues. I just find it odd that its as if you and him never happend almost like a disassociated fugue minus the amnesia ......